In the wireless communication system, often there are cases that devices are interconnected to constitute a network. These devices are interconnected through physical mediums, such as optical fibers, cables, etc. Generally two physical links are required to implement the interconnection, one is a physical downlink, that is, a link from a near-end device to a remote device; the other is a physical uplink, that is, a link from a remote device to a near-end device. When interruption occurs in these physical links due to anomaly, the normal operation of the system will be influenced. In order to locate the failure rapidly and accurately and maintain the links, a method for accurately and reliably detecting the physical link failures is required to be provided.
At present, in the wireless communication system, there are many common methods for detecting the physical link failure. Interruption of the physical uplink generally can be detected more easily. For example, interruption of an optical fiber can be determined based on an aphotic indication of an optical receiving module; interruption of a cable can be determined based on the existence or nonexistence of a signal. However, in the case of interruption of the physical downlink, generally information is required to be reported by the physical uplink and then the physical downlink is detected based on the reported information.
However, when the failure occurs in the physical downlink, even in the case that the physical downlink has been interrupted as the device is on, the remote device is unable to recover a line clock normally. Therefore a phase-locked loop of the remote device loses lock due to loss of reference time, and generally the physical uplink also becomes instable such that its reported failure information or some other important information possibly can not correctly reach the near-end device. So the existing method for detecting the physical downlink failure often can only determine that there are problems in the physical link, but can not determine whether the physical downlink failure or other reasons cause instability of the physical downlink such that it is difficult to determine whether the failure occur in the physical downlink, thus increasing the complexity of maintenance and failure processing of the physical downlink. Generally the maintenance personnel may be required to arrive at site to determine whether the failure occur in the physical downlink using a dedicated test device.